[blink] Support (semi-)transparent background colors in WebView/Frame.

third_party/WebKit/Source/core/frame/FrameView.cpp

Index: third_party/WebKit/Source/core/frame/FrameView.cpp
diff --git a/third_party/WebKit/Source/core/frame/FrameView.cpp b/third_party/WebKit/Source/core/frame/FrameView.cpp
index 9e3e71408ab44b0965cd124d0b0e2d83e0f629b5..39864ac75be23d07b0678e581e7a046c620c90fd 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameView.cpp
@@ -174,7 +174,6 @@ FrameView::FrameView(LocalFrame& frame)
           TaskRunnerHelper::get(TaskType::UnspecedTimer, &frame),
           this,
           &FrameView::updatePluginsTimerFired),
-      m_isTransparent(false),
       m_baseBackgroundColor(Color::white),
       m_mediaType(MediaTypeNames::screen),
       m_safeToPropagateScrollToParent(true),
@@ -2328,20 +2327,8 @@ void FrameView::setNeedsLayout() {
   layoutViewItem.setNeedsLayout(LayoutInvalidationReason::Unknown);
 }
 
-bool FrameView::isTransparent() const {
-  return m_isTransparent;
-}
-
-void FrameView::setTransparent(bool isTransparent) {
-  m_isTransparent = isTransparent;
-  DisableCompositingQueryAsserts disabler;
-  if (!layoutViewItem().isNull() &&
-      layoutViewItem().layer()->hasCompositedLayerMapping())
-    layoutViewItem().layer()->compositedLayerMapping()->updateContentsOpaque();
-}
-
 bool FrameView::hasOpaqueBackground() const {
-  return !m_isTransparent && !m_baseBackgroundColor.hasAlpha();
+  return !m_baseBackgroundColor.hasAlpha();
 }
 
 Color FrameView::baseBackgroundColor() const {
@@ -2365,13 +2352,11 @@ void FrameView::setBaseBackgroundColor(const Color& backgroundColor) {
     page()->animator().scheduleVisualUpdate(m_frame.get());
 }
 
-void FrameView::updateBackgroundRecursively(const Color& backgroundColor,
-                                            bool transparent) {
-  forAllNonThrottledFrameViews(
-      [backgroundColor, transparent](FrameView& frameView) {
-        frameView.setTransparent(transparent);
-        frameView.setBaseBackgroundColor(backgroundColor);
-      });
+void FrameView::updateBaseBackgroundColorRecursively(
+    const Color& baseBackgroundColor) {
+  forAllNonThrottledFrameViews([baseBackgroundColor](FrameView& frameView) {

[dcheng, 2017/03/31 01:21:15]

Btw, I'm wondering something: we only call this from LocalFrame::createView. But
at that point, we have a new LocalFrame/FrameView, right? So how is it possible
there are any children here?

[Eric Seckler, 2017/03/31 08:32:28]

I'm not sure if there is a way for children to be around in createView - I'm not
familiar enough with when we actually (re)create a view and if we're guaranteed
no children at those times.

But we're also calling this from WebViewImpl::updateBaseBackgroundColor now, so
that the WebView's overrides (for transparency in particular) are applied in all
children too.

So since there's some need for the method anyway, I'll play it safe and keep the
call in createView, too, for now. :)

+    frameView.setBaseBackgroundColor(baseBackgroundColor);
+  });
 }
 
 void FrameView::scrollToFragmentAnchor() {